Heavy rain is due to arrive in southern Britain within 24 hours as a prelude to one of the most powerful storms to hit the country in decades.

As hurricane-strength winds sweep in from the Atlantic, parts of England and Wales can expect nearly two inches of rain in a six hour period - enough to cause some localised flooding.

Forecasters say the exact arrival time and course of the winds remains uncertain. But predictions of the main area to be hit remain largely unchanged, with the storm expected to affect large swatches of England in a band south of mid-Wales to the Wash.

The peak of the storm is currently predicted to be between 3am and 6am on Monday, with winds of up to 70mph in the affected area and gusts of up to 80mph battering the south coast and exposed areas.

“We expect strong winds, possibly up to 70mph in some inland areas and 80mph on the coast,” said Eleanor Crompton, a Met Office forecaster.

“The wind is our greatest concern but in terms of rain it looks as if the highest total throughout the event may be around 70mm [two and a half inches] in isolated locations.

“There is a risk of some parts getting 50mm [two inches] in a six hour period.”

The Met Office tweeted this forecast for the storm (MET OFFICE)

People living in the affected parts of England and Wales have been advised to prepare for the high winds by lashing down garden furniture and other loose outdoor items.

Darron Burness, head of the AA's flood rescue team, said: "If the predicted storm strikes, the timing couldn't really be worse, potentially causing significant travel disruption on Monday morning, which is one of the busiest times on the roads.

"Strong wind and torrential rain is an unpredictable and hazardous combination, which can be quite overwhelming when you're driving.

"There's likely to be tree and other debris on the roads as well potential flooding, so it's very important to keep your speed down and drive with great care, particularly on country roads early on Monday morning when it's still dark."

The storm is expected to last until late on Monday evening.

The weather system has been caused by an area of extremely low pressure and fuelled by the remnants of two storms from the North American continent.

Nick Prebble, a forecaster at MeteoGroup, said: “There will still be some uncertainty about the nature of storm over the next 24 to 36 hours.

“There are still some question marks over what the strongest gusts will be.

“Heavy rain will precede the strongest winds and I wouldn’t be surprised if it caused localised flooding, particularly as some parts will have saturated ground from showers today. The rain will ease as the winds come in.”